Rab Dimi, son of Nehemiah, son of Rav Yosef [in Sanhedrin (23b, 24a) the version is "son of Rav Nachman, son of Rav Yosef," and perhaps the version before the genealogies is "son of Nehemiah, son of Rabbi Yochanan," because Rabbi Nehemiah, son of Yosef, is mentioned many times in the Talmud.
However, it requires further investigation why Rav Nachman, son of Yosef, is brought here]:
Seder_HaDorot,_Tanaim_and_Amoraim.919:1